rtmutex_api.c | Explore in Territory

// SPDX-License-Identifier: GPL-2.0-only
/*
 * rtmutex API
 */
#include <linux/spinlock.h>
#include <linux/export.h>

#define RT_MUTEX_BUILD_MUTEX
#include "rtmutex.c"

/*
 * Max number of times we'll walk the boosting chain:
 */
int max_lock_depth = …;

/*
 * Debug aware fast / slowpath lock,trylock,unlock
 *
 * The atomic acquire/release ops are compiled away, when either the
 * architecture does not support cmpxchg or when debugging is enabled.
 */
static __always_inline int __rt_mutex_lock_common(struct rt_mutex *lock,
						  unsigned int state,
						  struct lockdep_map *nest_lock,
						  unsigned int subclass)
{ … }

void rt_mutex_base_init(struct rt_mutex_base *rtb)
{ … }
EXPORT_SYMBOL(…);

#ifdef CONFIG_DEBUG_LOCK_ALLOC
/**
 * rt_mutex_lock_nested - lock a rt_mutex
 *
 * @lock: the rt_mutex to be locked
 * @subclass: the lockdep subclass
 */
void __sched rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass)
{ … }
EXPORT_SYMBOL_GPL(…);

void __sched _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock)
{ … }
EXPORT_SYMBOL_GPL(…);

#else /* !CONFIG_DEBUG_LOCK_ALLOC */

/**
 * rt_mutex_lock - lock a rt_mutex
 *
 * @lock: the rt_mutex to be locked
 */
void __sched rt_mutex_lock(struct rt_mutex *lock)
{
	__rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, 0);
}
EXPORT_SYMBOL_GPL(rt_mutex_lock);
#endif

/**
 * rt_mutex_lock_interruptible - lock a rt_mutex interruptible
 *
 * @lock:		the rt_mutex to be locked
 *
 * Returns:
 *  0		on success
 * -EINTR	when interrupted by a signal
 */
int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * rt_mutex_lock_killable - lock a rt_mutex killable
 *
 * @lock:		the rt_mutex to be locked
 *
 * Returns:
 *  0		on success
 * -EINTR	when interrupted by a signal
 */
int __sched rt_mutex_lock_killable(struct rt_mutex *lock)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * rt_mutex_trylock - try to lock a rt_mutex
 *
 * @lock:	the rt_mutex to be locked
 *
 * This function can only be called in thread context. It's safe to call it
 * from atomic regions, but not from hard or soft interrupt context.
 *
 * Returns:
 *  1 on success
 *  0 on contention
 */
int __sched rt_mutex_trylock(struct rt_mutex *lock)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * rt_mutex_unlock - unlock a rt_mutex
 *
 * @lock: the rt_mutex to be unlocked
 */
void __sched rt_mutex_unlock(struct rt_mutex *lock)
{ … }
EXPORT_SYMBOL_GPL(…);

/*
 * Futex variants, must not use fastpath.
 */
int __sched rt_mutex_futex_trylock(struct rt_mutex_base *lock)
{ … }

int __sched __rt_mutex_futex_trylock(struct rt_mutex_base *lock)
{ … }

/**
 * __rt_mutex_futex_unlock - Futex variant, that since futex variants
 * do not use the fast-path, can be simple and will not need to retry.
 *
 * @lock:	The rt_mutex to be unlocked
 * @wqh:	The wake queue head from which to get the next lock waiter
 */
bool __sched __rt_mutex_futex_unlock(struct rt_mutex_base *lock,
				     struct rt_wake_q_head *wqh)
{ … }

void __sched rt_mutex_futex_unlock(struct rt_mutex_base *lock)
{ … }

/**
 * __rt_mutex_init - initialize the rt_mutex
 *
 * @lock:	The rt_mutex to be initialized
 * @name:	The lock name used for debugging
 * @key:	The lock class key used for debugging
 *
 * Initialize the rt_mutex to unlocked state.
 *
 * Initializing of a locked rt_mutex is not allowed
 */
void __sched __rt_mutex_init(struct rt_mutex *lock, const char *name,
			     struct lock_class_key *key)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * rt_mutex_init_proxy_locked - initialize and lock a rt_mutex on behalf of a
 *				proxy owner
 *
 * @lock:	the rt_mutex to be locked
 * @proxy_owner:the task to set as owner
 *
 * No locking. Caller has to do serializing itself
 *
 * Special API call for PI-futex support. This initializes the rtmutex and
 * assigns it to @proxy_owner. Concurrent operations on the rtmutex are not
 * possible at this point because the pi_state which contains the rtmutex
 * is not yet visible to other tasks.
 */
void __sched rt_mutex_init_proxy_locked(struct rt_mutex_base *lock,
					struct task_struct *proxy_owner)
{ … }

/**
 * rt_mutex_proxy_unlock - release a lock on behalf of owner
 *
 * @lock:	the rt_mutex to be locked
 *
 * No locking. Caller has to do serializing itself
 *
 * Special API call for PI-futex support. This just cleans up the rtmutex
 * (debugging) state. Concurrent operations on this rt_mutex are not
 * possible because it belongs to the pi_state which is about to be freed
 * and it is not longer visible to other tasks.
 */
void __sched rt_mutex_proxy_unlock(struct rt_mutex_base *lock)
{ … }

/**
 * __rt_mutex_start_proxy_lock() - Start lock acquisition for another task
 * @lock:		the rt_mutex to take
 * @waiter:		the pre-initialized rt_mutex_waiter
 * @task:		the task to prepare
 *
 * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock
 * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that.
 *
 * NOTE: does _NOT_ remove the @waiter on failure; must either call
 * rt_mutex_wait_proxy_lock() or rt_mutex_cleanup_proxy_lock() after this.
 *
 * Returns:
 *  0 - task blocked on lock
 *  1 - acquired the lock for task, caller should wake it up
 * <0 - error
 *
 * Special API call for PI-futex support.
 */
int __sched __rt_mutex_start_proxy_lock(struct rt_mutex_base *lock,
					struct rt_mutex_waiter *waiter,
					struct task_struct *task)
{ … }

/**
 * rt_mutex_start_proxy_lock() - Start lock acquisition for another task
 * @lock:		the rt_mutex to take
 * @waiter:		the pre-initialized rt_mutex_waiter
 * @task:		the task to prepare
 *
 * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock
 * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that.
 *
 * NOTE: unlike __rt_mutex_start_proxy_lock this _DOES_ remove the @waiter
 * on failure.
 *
 * Returns:
 *  0 - task blocked on lock
 *  1 - acquired the lock for task, caller should wake it up
 * <0 - error
 *
 * Special API call for PI-futex support.
 */
int __sched rt_mutex_start_proxy_lock(struct rt_mutex_base *lock,
				      struct rt_mutex_waiter *waiter,
				      struct task_struct *task)
{ … }

/**
 * rt_mutex_wait_proxy_lock() - Wait for lock acquisition
 * @lock:		the rt_mutex we were woken on
 * @to:			the timeout, null if none. hrtimer should already have
 *			been started.
 * @waiter:		the pre-initialized rt_mutex_waiter
 *
 * Wait for the lock acquisition started on our behalf by
 * rt_mutex_start_proxy_lock(). Upon failure, the caller must call
 * rt_mutex_cleanup_proxy_lock().
 *
 * Returns:
 *  0 - success
 * <0 - error, one of -EINTR, -ETIMEDOUT
 *
 * Special API call for PI-futex support
 */
int __sched rt_mutex_wait_proxy_lock(struct rt_mutex_base *lock,
				     struct hrtimer_sleeper *to,
				     struct rt_mutex_waiter *waiter)
{ … }

/**
 * rt_mutex_cleanup_proxy_lock() - Cleanup failed lock acquisition
 * @lock:		the rt_mutex we were woken on
 * @waiter:		the pre-initialized rt_mutex_waiter
 *
 * Attempt to clean up after a failed __rt_mutex_start_proxy_lock() or
 * rt_mutex_wait_proxy_lock().
 *
 * Unless we acquired the lock; we're still enqueued on the wait-list and can
 * in fact still be granted ownership until we're removed. Therefore we can
 * find we are in fact the owner and must disregard the
 * rt_mutex_wait_proxy_lock() failure.
 *
 * Returns:
 *  true  - did the cleanup, we done.
 *  false - we acquired the lock after rt_mutex_wait_proxy_lock() returned,
 *          caller should disregards its return value.
 *
 * Special API call for PI-futex support
 */
bool __sched rt_mutex_cleanup_proxy_lock(struct rt_mutex_base *lock,
					 struct rt_mutex_waiter *waiter)
{ … }

/*
 * Recheck the pi chain, in case we got a priority setting
 *
 * Called from sched_setscheduler
 */
void __sched rt_mutex_adjust_pi(struct task_struct *task)
{ … }

/*
 * Performs the wakeup of the top-waiter and re-enables preemption.
 */
void __sched rt_mutex_postunlock(struct rt_wake_q_head *wqh)
{ … }

#ifdef CONFIG_DEBUG_RT_MUTEXES
void rt_mutex_debug_task_free(struct task_struct *task)
{ … }
#endif

#ifdef CONFIG_PREEMPT_RT
/* Mutexes */
void __mutex_rt_init(struct mutex *mutex, const char *name,
		     struct lock_class_key *key)
{
	debug_check_no_locks_freed((void *)mutex, sizeof(*mutex));
	lockdep_init_map_wait(&mutex->dep_map, name, key, 0, LD_WAIT_SLEEP);
}
EXPORT_SYMBOL(__mutex_rt_init);

static __always_inline int __mutex_lock_common(struct mutex *lock,
					       unsigned int state,
					       unsigned int subclass,
					       struct lockdep_map *nest_lock,
					       unsigned long ip)
{
	int ret;

	might_sleep();
	mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip);
	ret = __rt_mutex_lock(&lock->rtmutex, state);
	if (ret)
		mutex_release(&lock->dep_map, ip);
	else
		lock_acquired(&lock->dep_map, ip);
	return ret;
}

#ifdef CONFIG_DEBUG_LOCK_ALLOC
void __sched mutex_lock_nested(struct mutex *lock, unsigned int subclass)
{
	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_);
}
EXPORT_SYMBOL_GPL(mutex_lock_nested);

void __sched _mutex_lock_nest_lock(struct mutex *lock,
				   struct lockdep_map *nest_lock)
{
	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, nest_lock, _RET_IP_);
}
EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock);

int __sched mutex_lock_interruptible_nested(struct mutex *lock,
					    unsigned int subclass)
{
	return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, subclass, NULL, _RET_IP_);
}
EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);

int __sched mutex_lock_killable_nested(struct mutex *lock,
					    unsigned int subclass)
{
	return __mutex_lock_common(lock, TASK_KILLABLE, subclass, NULL, _RET_IP_);
}
EXPORT_SYMBOL_GPL(mutex_lock_killable_nested);

void __sched mutex_lock_io_nested(struct mutex *lock, unsigned int subclass)
{
	int token;

	might_sleep();

	token = io_schedule_prepare();
	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_);
	io_schedule_finish(token);
}
EXPORT_SYMBOL_GPL(mutex_lock_io_nested);

#else /* CONFIG_DEBUG_LOCK_ALLOC */

void __sched mutex_lock(struct mutex *lock)
{
	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
}
EXPORT_SYMBOL(mutex_lock);

int __sched mutex_lock_interruptible(struct mutex *lock)
{
	return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, NULL, _RET_IP_);
}
EXPORT_SYMBOL(mutex_lock_interruptible);

int __sched mutex_lock_killable(struct mutex *lock)
{
	return __mutex_lock_common(lock, TASK_KILLABLE, 0, NULL, _RET_IP_);
}
EXPORT_SYMBOL(mutex_lock_killable);

void __sched mutex_lock_io(struct mutex *lock)
{
	int token = io_schedule_prepare();

	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
	io_schedule_finish(token);
}
EXPORT_SYMBOL(mutex_lock_io);
#endif /* !CONFIG_DEBUG_LOCK_ALLOC */

int __sched mutex_trylock(struct mutex *lock)
{
	int ret;

	if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task()))
		return 0;

	ret = __rt_mutex_trylock(&lock->rtmutex);
	if (ret)
		mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);

	return ret;
}
EXPORT_SYMBOL(mutex_trylock);

void __sched mutex_unlock(struct mutex *lock)
{
	mutex_release(&lock->dep_map, _RET_IP_);
	__rt_mutex_unlock(&lock->rtmutex);
}
EXPORT_SYMBOL(mutex_unlock);

#endif /* CONFIG_PREEMPT_RT */
linux/kernel/locking/rtmutex_api.c
